Finishing of the Blacksmith's products

Translated from Metallurg, No. 12, pp. 44–47, December, 1991.     

Reconfigurable arrays by phase-only control

Due to space or cost reasons, a single array antenna can be required to radiate more than one pattern, each pattern being selected by an electronic control, in which only the phase can be modified. A synthesis method for such a problem that is able to determine both the common amplitude and the various phases in an integrated way is presented. Moreover, the approach is flexible enough to take into account additional constraints and allows an efficient implementation. Some test cases showing the effectiveness of the method are presented     

Vector-controlled induction motor drive with a self-commissioningscheme

Different vector-controlled structures are discussed, and their suitability for an economical and reliable industrial drive system is explored. From this, the design of a compact control hardware is derived, composed of an 80196 microcontroller and an ASIC (application-specific integrated circuit) for the generation of the pulsewidth modulation (PWM) signals. The drive system can be configured from a host computer or a hand-held servicing unit through a serial data link. Monitoring and diagnostic functions are included. A self-commissioning scheme permits the setting of the parameters for optimum dynamic performance of the induction motor. Various oscillograms demonstrate the behavior of the vector controller operating a 25-kVA PWM inverter     

Methods to assess physical activity with special reference tomotion sensors and accelerometers

Motion sensors may be applied for the assessment of physical activity. This paper reviews the evolution of these instruments from the mechanical pedometer to the electronic accelerometer. We conclude that for accurate assessment of physical activity under free living conditions the recently introduced accelerometer looks most promising, although little information was available regarding the reliability of these instruments. Subsequently, reliability of an accelerometer with a three-directional sensor was examined. Intrainstrument variation in a bench test was less than 8% during four measurements over a week. Interinstrument variation during treadmill experiments while subjects wore two accelerometers at the same time was on average 22% and was not improved after adjustment for differences found in the bench test. Reproducibility in the treadmill experiment was approximately 76, 85, and 95% at 3, 5, and 7 km/h, respectively. Bench testing revealed that the sensitivity of a piezoelectric element is prone to shifts, probably due to mechanical, electromagnetic, and/or temperature shock, which may be encountered during outdoor application. However, the relevance of the bench test in this study may be questioned, as results did not correspond with the findings in subjects. This needs further investigation.     

New results in spectral estimation of decimated processes

The aim of this letter is to derive the spectral density of decimated processes, and to establish their model when they are generated from ARMA processes. The optimal conditions of decimation are also discussed.<>     

Approximate account of double gas throttling in the pressurization openings of gas bearings

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 8, pp. 20–22, August, 1991.     

PROGRESS IN THE MODELLING OF AIR FLOW PATTERNS IN TIMBER KILNS

Progress in modelling air flow patterns in timber kilns using Computational Fluid Dynamics is reviewed in this work. These simulations are intended to predict the distribution of the flow in the fillet spaces between boards in a hydraulic model of a timber kiln. Here, the flow regime between the boards is transitional between laminar and turbulent flow, with Reynolds numbers of the order of 5000. Running the simulation as a transient calculation has shown few problems with convergence issues, reaching a mass residual of 0.2% of the total inflow after 40-100 iterations per time step for time steps of 0.01 s. Grid sensitivity studies have shown that non-uniform grids are necessary because of the sudden changes in flow cross section, and the flow simulations are insensitive to grid refinement for non-uniform grids with more than 300,000 cells. The best agreement between the experimentally-measured flow distributions between fillet spaces and those predicted by the simulation have been achieved for (effective) bulk viscosities between the laminar viscosity for water and ten times that value. This change in viscosity is not very large (less than an order of magnitude), given that effective turbulent viscosities are typically several orders of magnitude greater than laminar ones. This result is consistent with the transitional flows here.     

Flow and heat transfer in outlet pipes of cryostatting systems

Flow and heat transfer at mixed convection in the vertical channel connecting a cryogenic vessel and a room temperature zone are considered. The two-dimensional problem of conjugated heat transfer in the metal wall of the channel and in its cavity is solved by the finite difference method. The calculated values of the heat flux into the cold zone and of the temperature of the hot pipe end at different channel wall thicknesses, lengths, diameters, helium flowrates, as well as at different constants of the interaction of heat with the environment are given.A. V. Lykov Heat and Mass Transfer Institute, Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 63, No. 6, pp. 665–672, December, 1992.     

Grigorii Valentinovich Samsonov: Novosibirsk Period in the Study of Borides

This paper, dedicated to the memory of Grigorii Valentinovich Samsonov (15 February 1918 – 22 December 1975) [1, 2], corresponding member of the Ukrainian Academy of Sciences, gives a brief survey of the fruitful cooperation of this prominent researcher in materials science with the scientific community of the city of Novosibirsk. Results that have come from cooperation with G. V. Samsonov are unique indeed. They are related to the study of phase equilibria in boron-containing systems, mechanisms of interactions between boron and metals, and synthesis of high-melting borides (in particular, in the ultradisperse state). A vast amount of research has been focused on the development of coatings based on various modifications of boron nitride and related materials.     

Catalyst for desulfurization of high-end-point diesel fuel

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 34–35, March, 1992.